Grooved tie bar assembly for diecasting machines and the like



Oct. 29, 1968 E. D. PRINCE 3,407,685

GROOVED TIE BAR ASSEMBLY FOR DIECASTING MCHINES AND THE LIKE Filed April` 12, 196e 3:5; "i F6' 4 Y Y INVENTOR.

BY @if United safes Patent o 3,407,685 GROOVED TIE BAR ASSEMBLY FOR DIECASTING MACHINES AND THE LIKE Edgar D. Prince, Holland, Mich., assignor to Prince Manufacturing Company, Inc., Holland, Mich., a corporation of Michigan t Filed Apr. 12, 1966, Ser. No. 542,055 8 Claims. (Cl. 74-579) ABSTRACT F THE DISCLOSURE A tie rod apparatus particularly adapted for utilization iu conjunction with a press, pressure molding device or the like having an elongated tension member adapted to pass through the spaced front and rear plates of the apparatus. The member is not threaded at its extremities, but rather a sleeve is telescopically positioned thereover and the bearing nut adjustably affixed to the sleeve. The sleeve is retained on the member by means of a collar mating with a suitable groove in the extremity of the tension member. It is understood that this abstract is not to be utilized to limit the scope of this invention.

This invention relates to tie bars and, more particularly, to tie bars particularly adapted for utilization in diecasting and similar types -of machines which during the course of their normal operation, exert extremely high tension forces between components.

In the art of hydraulic pressing and diecasting, a movable member is converged toward a stationary member and the material to be pressed is placed therebetween. If the machine is a diecasting machine, the front and rear dies are also placed between the converging members. Obviously, during these operations it is necessary that the reference member to which the power source is attached and the stationary member remain in xed relationship with respect to one another.

It has become customary in the art to physically connect the reference member or back plate to which the prime mover is affixed to the stationary member or front plate by means of one or a plurality of tie rods. The movable member or plate then traverses back and forth between the back and front plates. As it converges towards the front plate, any material placed therebetween will be subjected to compression forces. These forces will be transferred from the front plate as tension forces back to the back plate via the tie rods.

Tie rods currently available for this purpose consist in one form or another of an elongated bearing member having its outer circumference threaded along each end. The elongated member is inserted into mating apertures within the front and back plates and a large nut is screwed onto each of its threaded extremities. Forces applied against the front plate are transmitted initially to the tie rod nut at the front plate, from the nut to the rod, from the rod to the nut at the other extremity thereof and finally to the back plate.

In order that the front and back plates may be positively adjusted with respect to one another so as to allow the utilization of different width dies and the pressing of relatively narrow as well as relatively wide objects, one of the extremities of the tie rod is usually threaded for a substantial distance along the length thereof whereby the distance between the front and back plates may be adjusted by turning the nut associated with that particular extremity so as to shorten the effective bearing length between the two plates. This turning may be accomplished by hand or, alternatively, may be done by a gearing arrangement from a suitable power source.

These types of tie bars have not been particularly successful for a number of reasons. Initially, they are very expensive to make because of the high tolerances required in the threading operation. The tie bars often run as much as ten to twenty feet in length and the difculties of machining an article of this size are apparent. Another problem which exists in tie rods currently available is that when the rods are threaded, their capabilities of withstanding large tension forces are markedly reduced, thus necessitating eitherV the use of a larger rod or constant replacement of the rods due to fracture. As

is well-known, the V-shaped threads which are ordinarily used for this purpose create tension concentrations around their bases which operate to reduce the tension bearing capabilities of the rod in a manner which may not be simply calculated by merely subtracting the cross-sectional area removed during the threading operation.

Finally, in the event that the rod should fracture at one of the threaded locations, it is necessary to replace the entire rod. This, of course, results in the rather inefficient utilization of material since the remainder of the rod is still in good condition but must be discarded.

It is an object of this invention to provide a tie rod assembly which is not subject to the above outlined disadvantages.

More particularly, it is an object of this invention to provide a tie bar which need not be threaded on its extremities and, thus, which will not have its tension bearing capabilities markedly reduced by the threading operation.

It is an object of this invention to provide a tie bar assembly wherein the forces exerted on the threadable member which renders the mechanism adjustable will be in compression rather than tension. This, of course, markedly increases the bearing capabilities for any given type of metal.

It is an object of this invention to provide a tie bar assembly wherein the machining required for manufacture of the tension bearing member itself is kept at a minimum, thus reducing the manufacturing cost considerably.

It is another object of this invention. to provide a tie bar assembly wherein, should a failure in the threaded or adjustable component occur, it is not: necessary to discard the entire tie rod but is necessary merely to replace that component of the tie rod assembly having the adjustment threads thereon, thus reducing the maintenance and operation expenses for machines embodying the tie rod.

These and other objects of this invention Will be readily understood by reference to the following specification and accompanying gures in which:

FIG. l is a partially fragmentary, broken plan View of the grooved tie bar assembly indicating the manner in which it is affixed to the front and back plates of the particular machine in which it is to be employed;

FIG. 2 is a cross-sectional View taken along line II-II of FIG. l;

FIG. 3 is a schematic plan view of a typical diecasting machine embodying the tie rod which is the subject of the instant invention; and

FIG. 4 is a schematic plan view of a typical hydraulic press employing the tie rod shown in FIG. 1.

Briefly, this invention comprises an elongated tension member having a threaded sleeve passed over and supported by one end thereof. Means are provided on the end of the tension bearing member to prevent the sleeve from passing thereover and thus olf from the bearing member. A bearing nut is turned onto the threaded sleeve and one of the plates of the particular machine in which the tie rod is a component bears against this nut.

The means for preventing the threaded sleeve from sliding oil from the elongated tension member comprises a circumferential groove` in the outerperiphe'ry of'the tension-member into which is inserted a split collar. The split collar extends radially 'from the outer periphery of the elongated tension `bearing member a sufficient distance to prevent the sleeve from sliding off the end thereof. i

Means are provided for retaining the bearing nut lin abutting relationship to the adjacent plate. These retaining means. are such that the nut may still be rotated with respect to the sleeve.

Two or more Itie rods may be utilized, for example, to connectl the -fronft and back-plates of a diecasting machine or a hydraulic press. In such a case, the moveable plate may be guided along its, reciprocating path by the tie rods. f

Referring now. to the figures, a preferred embodiment of this invention will be described lin detail. FIGS. l and 2 show a tie bar assembly 10 consisting of a cylindrical tension rod 11 having a circular collar retaining groove 12 machined in one end thereof and an identical circular collar retaining-groove 13 positioned in the other end thereof. A longitudinal key-slot 14 is additionally machined in the end of the cylindrical rod which is to support the adjustable bearing assembly 20.

' -A-sleeve 21 having an inner diameter approximately equal to the outer diameter of rod 11 and having a threaded periphery 22 is passed over rod 11.` The sleeve is prevented from coming back off rod 11 by means of a split collar 23 which is inserted into and mates with circular collar'retainer groove 13. A key24 is inserted into slot 14 and a mating slot in the edge of sleeve 21 such that the sleeve is radially fixed with respect to tie rod 11. Split collar 23 may be bolted together in a conventional manner and the entire assembly covered by a lock nut 25 having a threaded depending flange 26 which encircles split collar 23 and key 24 prior to screwing onto the extremity of the threaded periphery of sleeve 21.

A bearing nut 27 is threaded over sleeve 21 in a manner indicated in FIG. l. Conveniently, the bearing nut 27 may have a geared face 28 so as to allow mechanical rotation thereof and thus mechanical adjustment-of the tie bar assembly length. A retainer assembly 29 is affixed to the back plate of the particular machine in which the tie bar assembly is installed in order to prevent the back plate from separating away from bearing nut 27 when there is not tension on the tie rod.

At the opposite extremity of the cylindrical rod from the adjustable bearing assembly 20 there is positioned a stationary bearing assembly 30 which consists merely of a split collar 31 inserted into circular collar retainer groove 12. Split collar 31 may be identical to split collar 23v and may Vybe held in place by means of conventional bolts and a retainer assembly 32 suitably affixed to the front plate of the mechanism in which the tie bar assembly is incorporated.

When opposing forces are exerted against back plate 4 0 and front plate 41 they will be transmitted from front plate 41 to split collar 31 and from there to tension bearing rod 11. The force exerted on back plate will be transmitted to nut 27, to sleeve 21, to collar 23 and on to tension rod 11. Note that the threaded section of the assembly which renders the distance between the back plate `40and' the front plate 41 adjustable is in compression during the time that tension forces exist in rod 11. While the sheer forces existing on the threads of sleeve 21 cannot be ignored, it has been found that if nut 27 is suiciently wide the weakest point in the assembly will be the cross-sectional stress on sleeve 21. Since this stress is of a compression nature, the sleeve is highly unlikely to fracture under loading conditions because of the relatively high forces which most materials are capable of withstanding in compression.

This arrangement should be contrasted to that previously noted as old in the art. There the tension forces were transferred directly from the back plate and the abutting nut to the threadedrod itself. This 'left the threaded section of the rod in tension and markedly reduced the forces which it was capable of withstanding.

If, perchance, sleeve 21 should fail, it is apparent that all that need -be replacedfis-the sleeve itself. That is to say, that this inventionrenders it'isno longer necessary to replace the v'enti'retie bar assembly `when-a structural failure occurs in the threaded section'thereoflt is n'ecessary only to remove 'lock nut v25, retaineras sevrriblynv 29, 'split collar ,23fand keyv14.,The"sleeve` may then be slid off from the tension rod 11 and replaced.

Referring now to FIG. 3 there is shown in schematic fashion a typical diecasting machine incorporating the grooved tie bar assembly. which,is thesubject of this invention. There are three major force components.`These are the 'back plate 40, the front plate 41 and the movable 'plate 42 which is slidably mounted therebetween. Front plate 41 and back plate` 40 are connectedtoeach other by means of a pair of grooved 'tie bar'asserriblies 10` fabricated inaccordance with the teachings of this invention and'bear against their res'pectivefend plates'4 precisely Vas indicated"y in FIG. 1. Conveniently,'r`novable plate 42 may be journaled on tie bars 10 such that they act as a guide during its traverse into and out of casting relationship with front plate 41.

A conventional'hydraulic ram 43 having a conventional connecting link 44 affixed to the compression rod thereof is reciprocally affixed to movable plate 42 by rn'eans`of conventional diecasting toggle linkage indicated schematically at 45. The die plates 46 and 47 are inserted in the manner shown into the space between movable vplate 42 and front plate 41. As ram 43 is activated, connector link 44 moves to the right as viewed in FIG. 3. This causes toggle linkage 45 to begin to straighten, thus pushing movable plate 42 forward. Once the position 'shown' in solid lines in FIG. 3 has been reached, toggle linkage 45 locks and the die plates are held at the desired spacing for the desired length of time. Asrarh 43 is retracted, the toggle linkage 45 collapses and movable plate 42 is moved back into the position shown in phantom. Toggle linkage of the type shown schematically is utilized because of the great mechanical advantage which may be obtained thereby. 1

When it is desired to utilize different die plates, bearing nuts 27 on the adjustable bearing assemblies 20 ofthe individual tie rods may be rotated either'by handV or mechanically as a means of adjusting the spacing between movable plate 42 with its toggles in a locked position and front plate 41. This, as is well-known, allows the use of many' different types of dieswithin the 'same machine. It should also be noted that in the event it were desirable to markedly reduce the working width between movable plate 42 and front plate 41 or, for that matter, to markedly lengthen it, each of the rods 11 could be provided with a plurality of circular collar retaining grooves 13 along their length such that the entire adjustable bearing assembly 20` could be mo-ved to selected positions therealong, thus allowing a relatively coarse adjustment of the machine as well as the relatively line adjustment provided for by threaded sleeve 21.*'One 'such set of split collar retainer grooves is indicated Jby the reference'numeral 48 in FIG. l. The presence of this groove will not limit the travel of movable' plate 42 because of the journaling means associated therewith. On the'other hand, it will be 'apparent that vthreads could not be provided on the'rods to provide for this coarsean adjustment as the threads would be ruined when the machine was utilized with a relatively wide spacing between the movable plate in `its extended position and the front plate. It will be noted that when such-a coarse adjustment is provided different means must be utilizedto retain split collar 23 and keyj14 in theirl respective grooves.

Referring now to FIG. 4, a hydraulic press embodying the g'rooved tie bar assemblies which are the subject of this invention will be described in detail. The hydraulic i press consists of a front plate 50, a back plate 51 and a movable plate 52 supported for sliding movement between the two of them. A conventional hydraulic cylinder 53 is atiixed to back plate 51 by any wel1-known means and has its ram 55 extending therethrough and aixed to movable plate 52. A pair of grooved tie bar assemblies 10, fabricated in accordance with the teachings of this invention, maintain the spacial relationship of front plate 50 and back plate 51 at the desired interval. As noted with regard to FIG. 3, the movable plate 52 may conveniently be slidably borne by rod 11 of groove tie bar assembly by any well-known means such as linear bearing sleeve 54.

The article to be pressed is placed between front plate `50 and movable plate 52 and the hydraulic cylinder 53 is activated. This causes movable plate 52 to converge toward front plate 50 and thus exert a large compression force upon the article. This force is transmitted through the article to front plate 50 and back to back plate 51 via the two grooved tie bar assemblies 10 in the manner previously described.

As in the diecasting machine shown in FIG. 3, the distance between front plate 50 and back plate 51 may be varied by rotating nuts 27, either manually or by machine, in such a manner as to selectively close or widen the gap between the two plates. The retainers 29 and 32 prevent the plates to which they are attached from falling out of alignment during this process.

Thus it `will be seen that this invention has provided a grooved tie bar assembly capable of withstanding large tension forces and which does not subject threaded components necessitated by the mandatory adjustability of the bar to large tension forces. Little machining is required on the rod per se and in the event that the` threaded component should fail under compression, it is necessary to replace only that component of the assembly rather than discarding the entire tie bar. The length of the rod may be positively adjusted either by manual or mechanical means.

The particular diameter of rod 11, and thus the size of the various components of the grooved tie bar assembly, depends upon the particular unit into which it is to be incorporated. A diameter of five to ten inches for the rod component 11 would not be unusual. Alternatively, the principles disclosed therein apply equally as well to smaller tension loads and the grooved tie bar assembly which is the subject of this invention could be utilized in other types of load carrying environments. The stress bearing advantages obtained by utilizing the construction disclosed herein are similar regardless of the size of the rod 11 or of the magnitude of the load placed thereon.

While a preferred embodiment of this invention has been discolsed in detail, it will be apparent to those skilled in the art that many modifications thereof are possible without departing from the spirit and scope of this invention. Such modifications are to be deemed as included in the following claims unless these claims, by their language, expressly state otherwise.

I claim:

1. Apparatus of the character described comprising: first and second plate members positioned in spaced relationship with respect to one another; a tie rod assembly for retaining said first and second plate members in said spaced relationship despite the exertion of a spreading force therebetween, said assembly being particularly adapted for tension stress, said assembly having an elongated tension member; a threaded sleeve positioned around and supported at one extremity of that portion of said tension member which is to be in tension `when said force is exerted; a bearing nut means threadedj'on said sleeve, said means having a bearing surface facing toward the other extremity of said portion of said tension member, said sleevepassing through one of said plate members such that said one plate member abuts said bearing surface at least when said force is exerted; means for removably securing said sleeve to said tension member at said one extremity such that said sleeve will be in compression when a tension force is exerted on said assembly; and, means for securing the other extremity of said portion to the other of said plate members.

2. The combination as set forth in claim 1 in which said securing means comprises:

a collar retaining groove in sai dtension members; an

a retainer collar positioned Within said groove, said collar extending above the periphery of said member to form a shoulder against which said sleeve rests.

3. The combination as set forth in claim 2 wherein said member and said sleeve are circular.

4. The combination as set forth in claim 3 which further comprise a key means for preventing said sleeve from rotating with respect to said member.

5. Apparatus of the character described comprising a front plate; a back plate; a movable plate mounted for reciprocal movement between said front and back plates; a tie rod assembly connecting said front and back plates so as to retain them in fixed spatial relationship with respect to one another despite the exertion of a spreading force therebetween, said assembly having an elongated tension member with passes through aigned apertures in said front and back plates; a threaded sleeve positioned around and supported at one extremity of that portion of said tension member which is to be in tension when said force is exerted; a bearing nut means threaded on said sleeve, said bearing nut means having a bearing surface facing toward the other extremity of said portion of said tension member, said sleeve passing through the aperture in one of said front and back plates such that said one plate abuts said bearing surface at least when said force is exerted; means for removably securing said sleeve to said tension member at said one extremity such that said sleeve will be in compression when a tension force is exerted on said rod assembly; and means for securing the other extremity of said portion to the other of said front and back plates.

6. The combination as set forth in claim 5 in which said securing means comprises:

a collar retaining groove in said tension membes; and

a retainer collar positioned within said groove, said collar extending above the periphery of said mem- -ber to form a shoulder against which said sleeve rests.

7. In a machine having a front plate, a back plate and a movable plate mounted for reciprocal movement between said front and back plates, a tie rod apparatus for connecting said front plate to said back plate comprising: an elongated tension member passing through aligned apertures in said front and back plates;

a threaded sleeve passing over and supported by one end of said tension member;

a bearing nut threaded on said sleeve, said bearing nut adapted to abut the outer surface of one of saidV front and back plates;

a collar retaining groove in said tension member;

a retaining collar positioned within said groove, said collar extending above the periphery of said member to form a shoulder against which said sleeve rests whereby said sleeve can be prevented selectively from sliding off from said bearing member; and

means for retaining said bearing nut in abutting relationship to one of said front or lback plates, said means allowing said nut to be rotated with respect to said4 sleeve and said abutting plate.

8. The combination as set forth in claim 7 which further comprises a key means Ifor preventing said sleeve from rotating with respect to said member.

(References on following page) U.S. DEPARTMENT 0F COMMERCE PATENT OFFICE Washington,D.C. 20231 UNITED STATES PATENT GEEICE CERTIFICATE 0F CORRECTION Patent No. 3,407,685 October 29, 1968 Edgar D. Prince It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 26, "with" should read which line 26, "aigned" should read aligned line 44, "membes" should read member Signed and sealed this 17th day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, IR.

Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer 

